Grafika\Gd\Helper\GifHelper::open PHP Method

    public function open($imageFile)
    {
        $fp = fopen($imageFile, 'rb');
        // Binary read
        if ($fp === false) {
            throw new \Exception(sprintf('Error loading file: "%s".', $imageFile));
        }
        $size = filesize($imageFile);
        $bytes = fread($fp, $size);
        $bytes = unpack('H*', $bytes);
        // Unpack as hex
        $bytes = $bytes[1];
        fclose($fp);
        return new GifByteStream($bytes);
    }

 /**
  * Load a GIF image.
  *
  * @param string $imageFile
  *
  * @return Image
  * @throws \Exception
  */
 private static function _createGif($imageFile)
 {
     $gift = new GifHelper();
     $bytes = $gift->open($imageFile);
     $animated = $gift->isAnimated($bytes);
     $blocks = '';
     if ($animated) {
         $blocks = $gift->decode($bytes);
     }
     $gd = @imagecreatefromgif($imageFile);
     if (!$gd) {
         throw new \Exception(sprintf('Could not open "%s". Not a valid %s file.', $imageFile, ImageType::GIF));
     }
     return new self($gd, $imageFile, imagesx($gd), imagesy($gd), ImageType::GIF, $blocks, $animated);
 }